1. Field of the Invention
The present invention relates to a media feeding control apparatus for an ink-jet printer. More particularly, it relates to an apparatus for controlling the pressure acting on print media that is fed by an automatic paper feeding apparatus of an ink-jet printer according to the thickness of the print media.
2. Description of the Related Art
The prior art contains many examples of individual feeders capable of feeding both thick documents and thin, or regular thickness documents using a single apparatus. For example, U.S. Pat. No. 5,335,899 for an Apparatus And Method For Automatically Adjusting Sheet Feeding Pressure to Golicz discloses a high speed sheet feeder that automatically adjusts for a wide variation in sheet thickness during operation. When a thick sheet of paper is encountered, less pressure is exerted on the pick-up roller. When a thin sheet of paper is encountered, a greater amount of pressure is exerted to convey the sheet of paper.
U.S. Pat. No. 4,828,245 for a Sheet Feeder Suitable For Feeding Thick Sheets to Shimogawara discloses a sheet feeder that can feed both thin and thick sheets of paper. An attach rent attaches to the conventional sheet storage cassette to enable both thin and thick sheets to be conveyed.
U.S. Pat. No. 5,348,283 for a Sheet Feeding Apparatus Having Sheet Separating Means With Adjustable Feeding Force to Yanagi, et al. discloses a sheet feeding apparatus having a sheet separating means with adjustable feeding force. The apparatus allows for thicker sheets such as postcards, envelopes and the like as well as plain sheets of paper to be manually inserted or to be automatically inserted into the sheet feeding apparatus.
U.S. Pat. No. 4,838,535 for a Sheet Feeding Device With Detachable Holder Means For Thick Cut Sheets to Yokoi, et al. discloses sheet feeding device with a detachable holder means for thick cut sheets. A holder containing thick cut sheets such as postcard is detachably mounted on the supporting structure. Yokoi '535 is intended to be compact in design, easy to operate, and does not require any exclusive driving means for thick paper feed, thus reducing manufacturing cost.
Finally, U.S. Pat. No. 5,040,780 for a Sheet Feeding Apparatus For Separating Individual Sheets From Stacks of Sheets Of Different Relative Stiffness to Lohrmann, et al. discloses a sheet feeding apparatus for separating individual sheets from stacks of sheets having a different relative stiffness. The invention uses a space saving arrangement for effectively accommodating to and separating individual sheets of various thicknesses from stacks of sheets in a sheet feeding apparatus.
What is needed is a simplified sheet feeder that allows for both the feeding of regular thickness sheets and extra thick sheets into an image formation device. By a single manual manipulation, the sheet feeder can convert from conveying thick sheets to conveying of regular sheets and vice versa.